This application relates to implements formed from certain open-celled foams made from high internal phase emulsions.
The development of open-celled foams made from high internal phase emulsions, or HIPEs, has been the subject of substantial interest. These foams, termed HIPE foams hereinafter, have been cited for numerous potential uses. For example, U.S. Pat. No. 4,606,958 (Haq et al.) issued Aug. 19, 1986 describes an absorbent substrate such as a cloth or a towel prepared from a sulfonated styrenic HIPE foam for mopping up household spills. U.S. Pat. No. 4,536,521 (Haq) issued Aug. 20, 1985 describes similar HIPE foams which can act as ion exchange resins. U.S. Pat. No. 4,522,953 (Barby et al.) issued Jun. 11, 1985 describes use of HIPE foams as reservoirs for carrying liquids. U.S. Pat. No. 5,021,462 (Elmes et al.) issued Jun. 4, 1991 describes HIPE foams useful in a filter body, as a catalyst support, and as a containment system for toxic liquids. U.S. Pat. No. 4,659,564 (Cox et al.) issued Apr. 21, 1987 describes use of HIPE foams for absorbing axillary perspiration. U.S. Pat. No. 4,797,310 (Barby et al.) issued Jan. 10, 1989 describes HIPE foam substrates useful for delivering or absorbing liquids such as cleaning compositions. Other uses cited include hand and face cleaning, skin treatment other than cleaning, baby hygiene, cleaning, polishing, disinfecting, or deodorizing industrial and domestic surfaces, air freshening, perfume delivery, and hospital hygiene. U.S. Pat. No. 4,966,919 (Williams et al.) issued Oct. 30, 1990 describes use of certain HIPE foams for containing the deuterium/tritium fuel needed for a laser induced fusion reactor. U.S. Pat. No. 3,763,056 (Will) issued Oct. 2, 1973 discloses HIPE foams with numerous uses, including construction, furniture, toys, molded parts, casings, packaging material, filters, and in surgical and orthopedic applications. U.S. Pat. No. 3,256,219 (Will) issued Jun. 14, 1966 discloses uses wherein the HIPE is applied to a substrate prior to polymerization for use in insulation, flooring, wall and ceiling coverings or facings, as breathable artificial leather, separators for storage batteries, porous filters for gases and liquids, packing material, toys, for interior decoration, orthopedic devices, and as a cork substitute. U.S. Pat. No. 5,817,704 (Shiveley et al.) issued Oct. 6, 1998 discloses uses for heterogeneous HIPE foams including environmental waste oil sorbents, bandages and dressings, paint applicators, dust mop heads, wet mop heads, in fluid dispensers, in packaging, in shoes, in odor/moisture sorbents, in cushions, and in gloves. HIPE foams have also been cited for utility in disposable absorbent products such as diapers and catamenials. Exemplary patents are U.S. Pat. No. 5,650,222 (DesMarais et al.) issued Jul. 22, 1997 and U.S. Pat. No. 5,849,805 (Dyer) issued Dec. 15, 1998. The latter cites utility in bandages and surgical drapes, inter alia.
HIPE derived foams have been disclosed for use in air filtration. For example, WO 97/37745 (Chang et al.) published Oct. 16, 1997 discloses a filter material prepared from a porous substrate impregnated with a HIPE which is then polymerized. Two publications, Walsh et al. J. Aerosol Sci. 1996, 27(Suppl. 1), 5629-5630, and Bhumgara Filtration and Separation March 1995, 245, disclose the use of HIPE derived foams for air filtration. HIPE foams have also been used for insulation. U.S. Pat. No. 5,633,291 (Dyer et al.) issued May 27, 1997, U.S. Pat. No. 5,770,634 (Dyer et al.) issued Jun. 23, 1998, U.S. Pat. No. 5,728,743 (Dyer et al.) issued Mar. 17, 1998, and U.S. Pat. No. 5,753,359 (Dyer et al.) issued May 19, 1998 describe such foam materials used for insulation. The above patent and literature citations are included by reference.
One aspect of HIPE foams which has in some cases limited their utility has been the durability of these foams. In some potential applications, durability in terms of abrasion resistance, tear resistance, and toughness under shear or tensile loads is not provided at a level needed by HIPE foams described in the art. HIPE foams with comparatively higher abrasion resistance have been developed using a relatively high level of a toughening monomer such as styrene with respect to the level of crosslinking monomer within the formulation. Such formulations are described in more detail in provisional U.S. patent application Ser. No. 60/077,955, filed on Mar. 13, 1998 (PandG Case 7055P) and copending U.S. patent application Ser. No. 09/118,613, filed in the name of Conrad, et al. on Nov. 12, 1998. However, the art has failed to recognize the full utility of such toughened HIPE foams. Therefore, there is a need for foam-based implements having improved durability so as to provide increased utility to such implements. There is a further need for implements having increased flexibility in finished properties, such as fluid handling properties and mechanical properties. There is a still further need to provide implements having a diversity of shapes, both two-dimensional and tridimensional.
The present invention relates to the implements comprising open-celled polymeric foams are prepared by polymerization of certain water-in-oil emulsions having a relatively high ratio of water phase to oil phase, commonly known in the art as xe2x80x9cHIPEs.xe2x80x9d As used herein, polymeric foam materials which result from the polymerization of such emulsions are referred to hereafter as xe2x80x9cHIPE foams.xe2x80x9d
The implements of the present invention include those having a substantially two-dimensional structure, such as wipes, mats, shoe inserts, some artistic media, targets, medical wraps, and the like, and those having a substantially three-dimensional structure, such as, certain artistic media and toys, sponges, and the like. Other exemplary implements include fire starting materials, devices to aid food preparation, and plant care aids.
The HIPE foams used in the present invention comprise a nonionic polymeric low density, open celled, high surface area foam structure. These HIPE foams are formulated to provide a level of durability that makes them suitable for a wider range of uses than heretofore recognized. These HIPE foams have:
A) a density of less than about 100 mg/cc;
B) a glass transition temperature (Tg) of between about xe2x88x9240xc2x0 and about 50xc2x0 C.; and
C) a toughness index of at least about 75.
The present invention provides for the formation of these HIPE foams into useful implements described below. Such foams are prepared via polymerization of a HIPE comprising a discontinuous water phase and a continuous oil phase wherein the ratio of water to oil is at least about 10:1, preferably at least about 12:1, and more preferably at least about 15:1. The water phase generally contains an electrolyte and a water soluble initiator. The oil phase generally consists of substantially water-insoluble monomers polymerizable by free radicals, an emulsifier, and other optional ingredients defined below. The monomers are selected so as to confer the properties desired in the resulting polymeric foam, e.g., the glass transition (Tg) between about xe2x88x9240xc2x0 and 50xc2x0 C., abrasion resistance and/or toughness sufficient for the end use, and economy (reflected by the relatively low density of less than about 100 mg/cc).